dashboard: fix a bug that could not handle proxy requests correctly (#5326)

[ti-chi-bot]

This is an automated cherry-pick of #5326

What problem does this PR solve?

Issue Number: Close #5321

What is changed and how does it work?

Only process headers added by PD.

Check List

Tests

• Unit test

Related changes

• Need to cherry-pick to the release branch

Release note

Fix a bug that could not handle dashboard proxy requests correctly.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lhy1024
• nolouch

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[lhy1024]

ci failed

[nolouch]

/merge

[ti-chi-bot]

@nolouch: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

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[ti-chi-bot]

@nolouch: /merge in this pull request requires 2 approval(s).

In response to this:

/merge

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[nolouch]

/merge

[ti-chi-bot]

@nolouch: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 3feef33

[nolouch]

/merge

[ti-chi-bot]

@nolouch: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 2c4856d